"It is absolutely a disruptor and I think what we saw in Salisbury was a very clear 'I'm going to send this in...and see how the UK and its partners respond' because it is constantly pushing and testing the boundaries," Ms Clarke said.

She said the reaction to the nerve agent attack in Salisbury showed a "united and coordinated response".

The United States, United Kingdom, Germany and France jointly condemned Russia following the attack.

"We and all our partners said very clearly that the breaking of international law, the breaking of the chemical weapons convention and the attempted murder of people in another country's territory is not acceptable," Ms Clarke said.

British Prime Minister Theresa May said Russia is "highly likely" to be responsible for the attack. Asked whether 'highly likely' was enough to justify the retaliatory expulsions, Ms Clark said the UK was protecting its national interests, security and values.

"We are very confident that Russia was responsible for this Novichok and either it has lost control of it or it was sanctioned and we are very clear also that Russia’s response to it, to our request for further information, was inadequate," she said.

The attack, she added, was not just a concern for the UK but for the world.

"It is a violation of the chemical weapons convention, it is a violation of international law and it is part of a bigger picture of Russia's attempt to undermine the rules-based order, the rules-based order that we all depend on, particularly New Zealand as an independent trading nation," she said.

Britain is also at odds with Russia over its actions in Syria. Russia says the recent airstrikes by the UK, US and France were an "illegal act of aggression". Asked whether the Britain had acted illegally by bombing without an UN mandate, Ms Clarke said the attack met the legal criteria for humanitarian intervention.

"We took action to degrade Syria's chemical weapons capabilities because there is a pattern of attacks here and you have children dying in the most terrible situations. Yes we would all have liked a diplomatic solution, but Russia at the UN was constantly and consistently vetoing any attempt to have a formal investigation," she said.

"If Russia vetoes a diplomatic solution then I don't think the answer is to sit back and go 'sorry’ to the children who are suffering, ‘there is nothing we can do'. Sometimes you have to take action."

Ms Clarke said it was a "scary time" in terms of international security and like-minded international partners had to band together.

"You have all sorts of new threats that you didn't have during the Cold War, you have hostile cyber, you have hybrid threats, and I think that what we want to do is make sure we are working with like-minded partners like the NZ part of the Five Eyes, with NATO, with our European partners and with the US to shore up this international system".

Clarke said despite there being a lack of trust it was important to keep the channels open and work towards better relations.

"But that requires Russia to actually play by the rules and right now it is not."

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